Whipping cream, coffee whiteners, chilled and frozen dessert cream, confectionary cream and cooking cream are conventionally made of natural cream, or a substitute synthetic cream prepared from animal and vegetable fats and oils. Some of these products may be comprised of a mixture of natural cream and synthetic cream. Both natural and synthetic cream are an aqueous emulsion of fine oil globules, generally referred to as an oil-in-water emulsion. Since the outer phase of these creams is an aqueous phase containing protein, they are easily infested with molds, bacteria and other microorganisms. These creams are usually sterilized by heating at temperatures of about 70.degree. C. (sterilization at about 70.degree. C. is hereinafter referred to as low-temperature sterilization). However, since these creams cannot contain preservatives, they easily putrefy during storage in today's complicated distribution system. Accordingly, they only retain their commercial value for a short period.
In order to increase the storability of these creams, products that have been subjected to high-temperature sterilization (hereunder HTST) or ultra-high-temperature sterilization (hereunder UHT) as described in J. G. Zadow, The Australian Journal of Dairy Technology, pages 44-49 (June, 1969) and M. L. Aggarwal, J. Milk Food Technol., Vol. 38, No. 1, pages 36-38 (January, 1975) and which are packaged aseptically (such products are hereunder referred to as aseptic cream) have been introduced in the market. Aseptic cream can be stored in a sealed container for an extended period without spoiling. However, once the container is opened, the cream is contaminated by aerial microorganisms and putrefy very quickly. Natural cream and synthetic cream, as well as aseptic cream is perishable and whipped cream made therefrom gives off a detectable bad odor after 3 to 4 days of storage at 5.degree. to 10.degree. C. making it no longer commercially acceptable. Therefore, makers and distributors have always been harassed by the perishable nature of oil-in-water emulsions.
Although, long-keeping oil-in-water emulsions have been desired for many years, no perfect solution has been proposed. This is due to difficulties in improving the keeping quality of creams without impairing their performance, taste and flavor.
As a result of various studies to provide long-lived oil-in-water emulsions, the present inventors came to realize that improvements on the method of sterilization or packaging are not the right approach. Alternatively, the present inventors worked towards improving the composition of the oil-in-water emulsion itself. In connection with their work, the present inventors conducted many experiments on the antibacterial or microbiologically stable effect of adding natural compounds. Accordingly, the present inventors have found that the keeping quality of creams can be improved satisfactorily without impairing their characteristics and flavor by adding a combination of amino acids and saccharides to the creams.